The invention relates to an arrangement for carrying out a two-stage linear movement comprising a stationary and a movable constructional unit with an hydraulic cylinder with at least one filling valve and an hydraulic piston, preferably implemented as plunger, having a hollow volume and with a device for building up pressure in the hydraulic cylinder.
With various and diverse machinery it is required that machine parts carry out linear movements. Examples are machine tools, injection moulding machines and robots.
While in some machines it is of primary importance that the movement is carried out rapidly (for example in robots), other machines require primarily large forces.
In the case of injection moulding machines, for example in die clamping devices, the requirements change while the movement is in progress. During closure of the form tool, for example, the movable form half first needs to be moved as rapidly as possible in accordance with a given speed profile, wherein during this movement relatively little force needs to be expended whereupon during the continued movement a large pressure is necessary.
It is generally known that by means of mechanical devices, for example by means of helical drives, and here in particular by means of ball screws fast linear movements can be carried out. On the other hand, high pressure, in particular with hydraulic devices such as with hydraulic piston cylinder units, is achieved.